Rotatable multiple-lead electrical connector



y 1965 c. w. DANIELS 3,193,636

ROTATABLE MULTIPLE-LEAD ELECTRICAL CONNECTOR Filed Noy. 7, 1962 3 Sheets-Sheet 1 Cmzx. w. DANIELS ATTORNEYS c. w. DANIELS 3,193,636 flOTATABLE MULTIPLE-LEAD ELECTRICAL CONNECTOR July 6, 1965 3 Sheets-Sheet 2 Filed Nov. 7, 1962 INVENTOR CRIZL. w. DAmELs BY Z a/m K 6% ATTORNEYS United States Patent Office 3,193,636 Patented July 6, 1965 3,193,636 ROTATABLE MULTIPLE-LEAD ELECTRICAL CONNECTOR Carl W. Daniels, Newport, Ky., assignor to Avco Corporation, Cincinnati, Ohio, a corporation of Delaware Filed Nov. 7, 1962, Ser. No. 236,104 6 Claims. (Cl. 20051.12)

The present invention relates generally to multiplelead electrical connectors of the swivel type, and more particularly to a self-interlocking demountable swivel-type connector in which the internal contacts provide self-interlock features for the connector.

Swivel connectors which are designed to connect the ends of a pair of cables together generally comprise a female receptacle for housing the lead ends of one 'set of conductors of one cable, and a plug insertable into the receptacle for housing the lead ends of the set of conductors of the other cable. Conventional connectors are designed so that lead ends in the plug are soldered or otherwise attached to annular contact rings provided on the outer surface of the plug, and the lead ends of conductors in the receptacle are connected to internal contact rings secured to the receptacle. The contact rings mate when the plug is inserted into the receptacle thereby elfec'tingan electrical connection between the ends of the cables.

After the plug is inserted into the receptacle, the problem arises of preventing an unintentional breakage of the electrical contact by'forces applied to the cables or to the connector directly. The prior art has sought to overcome this problem by providing the connector with a locking device that permits limited rotative movement between the plug and the receptacle and yet limits or prevents electrical contact-breaking axial movement between these two parts. Conventional locking devices may, for example, take the form of a cap forthe plug which incapsulates the plug and threadedly connects the plug to the receptacle; or the locking device may take the form of a bolt that extends axially throughthe plug and receptacle and is threadedly connected to the receptacle so that the head of the bolt can limit contact-breaking movement between the plug and the receptacle.

Electrical assemblies may incorporate a considerable number of swivel-type multi-conductor connectors, and therefore it would be advantageous to eliminate the use of a locking device as well as the accompanying step of fastening the locking device to the receptacle after the plug has been sea-ted in the receptacle. In prior-art connectors that incorporate locking devices of the general type described briefly hereina-bove, if the particular locking device were not employed, only frictional engagement bet-ween the mating cont-acts would serve to hold the plug within the receptacle. By increasingthe frictional con tact between the mating contacts, the force which must be applied to effect contact-breaking separation also increases. Unfortunately, the increase in frictional engagement between the contacts also gives rise to the need for applying a correspondingly increased force to effect proper insertion of the plug into the receptacle.

Another disadvantage of known swivel-type connectors is the lack of a relatively simple mechanism for pushing the plug outwardly from the receptacle so that the lengths of the cables extending from the plug and the receptacle do not have tobe grasped and pulled apart to eifect separation-between the plug and receptacle. Particularly if the junction formed bythe internal contacts of the plug and the receptacle is relatively tight, pulling on the cable instead of the connector mayicause' breakage of the connection existing between-the lead ends of the cables and their contacts in the plug and receptacle of the cables andtheir contacts in the plug and receptacle of the connector. 7 I

The present invention is primarily directed to overcoming the aforementioned disadvantages of known swivel type multiconductor connectors, and. provides among other features, interlocking contact elements which mechanically interlock such that the force that must be applied to break contact between the elements must be considerably larger than the'force initially required to seat the plug in the receptacle. An additional feature of the invention is the provision of a relatively simple mechanism which can be actuated to push theplug out.- wardly from the receptacle 2. distance suflicient to break the interlock existing between the internal contacts'the'reby facilitating the removal of the plug from the receptacle.

Broadly, therefore, it is an object of this invention to provide a multiple-lead electrical connector of the swivel type wherein the internal electrical contacts self-interlock.

More specifically, it is an object of this invention to provide a multiple-lead connector of the swivel type inw eluding a plug and a receptacle for receiving the plug, wherein mating contacts affixed to the plug and receptacle respectively, permit relatively easy insertion of the plug into the receptacle but offer a considerably increased resistance to removal of the plug from the receptacle,

Another object of this invention is to proivde a swiveltype electrical connector having interlocked internal con, tacts, the connector including a mechanism operable to break the interlock existing between the internal contacts.

Still another object of this invention is to provide a self-interlocking multiple lead electrical connector including a plug and a receptacle having mating contact sections aflixed thereto, the plug and receptacle being rotatable relative to each other so that a lead connected to one contact section on the plug may be selectively connected to a lead connected to another and initially nonmating contact section on the receptacle.

Yet another object of this invention is to provide a self-interlocking multiple-lead connector including a receptacle and a plug seated in the receptacle and having mating internal contacts, the receptacle including a device for orienting the plug during insertion thereof into the receptacle so that proper electrical contact is effected between the internal contacts.

The above and still further objects, features and. advantages of the present invention will become apparent upon consideration of the following detailed description of one specific embodiment thereof, especially when taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a perspective view of a disconnected swivel-type multiple-lead connector in accordance with this invention; 7 V 7 FIGURE 2 is a sectional side View of the receptacle of the connector taken on line 22 of FIGURE 1;.

FIGURE 3 is an end view of the receptacle shown in FIGURE 1; V p I FIGURE 4 is a side view of the plug of the connector shown in FIGURE 1; i

FIGURE 5 is an end view of the plug shown in FIG- URE 4; V

FIGURE 6 illustrates another embodiment of the-con nector in accordance with this invention; 7

FIGURE 7 is a partial sectional side view of FIGURE 6 taken on line 77 of that figure; I W

FIGURE 8 is'a full sectional end" view of the embodiment shown in FIGURE 6 taken on line 8--S of FIG- URE 7;

FIGURE 9 is a partial sectional side viewof the receptacle and the plug seated in the receptacle, and additionally illustrates a mechanism for forcing the contacts on the plugfrom interlocking relationship with mating contacts in the receptacle;

FIGURE 13 vis a side view of another embodiment of I a plug for use with the receptacle shown in FIGURE 11; FIGURE 14 is a section View of FIGURE 13 taken on section line 1414 of that figure; and

FIGURE 15 illustrates a cross-section of an assembled connector embodying the plug and receptacle illustrated in an electrical installation for the purpose of securing the connector to that fixture or installation.

As shown in FIGURES 2, 4 and 7 of the accompanying drawings, the ring contacts 32, 33 and 34 are essentially of an inverted W shape, the V-shaped peripheral raceways or grooves 32a, 33a, and 340, respectively, formed intermediate theembedded ends of the contacts to receive the tips 14c, c and 160, respectively, as well as a relatively short section of the adjoining contact arms FIGURES 11-14, inclusive, the cross-section being taken 7 through section 1414.of .the plug.

Referring now to FIGURES 1 and 2 of the accompanying drawings for a more complete understanding of the present invention, the cylindrical connector 10 comprises a cylindrical receptacle 11 formed of an electrical insulating material, as for example, hard rubber. A conical bore 12 is formed in the receptacle 11 into which an essentially frusto-conical shaped plug 13 can be inserted and seated. Extending into the bore 12 are one or more finger-type contact elements, three of these elements be ing shown and designated by the numerals 14, 15 and 16, respectively. The contact elements 14, 15 and 16 are formed with ring-like bases 14a, 15a and 16a, respectively, which may be molded into, or otherwise secured to the conical wall forming the bore 12, the bases 14a, 15a and 16a respectively increasing in diameter an amount corresponding to the increase in diameter of the bore 12, The contact elements 14', .15 and 16 are segmented in order to provide a plurality of contact arms, one arm of each contact element 14, 15 and 16 being designated by the numeral 14b, 15b and 16b, respectively. The contact arms 14b,15b and 16b cantilever frornthe bases 14a, 15a and 16a, respectively, and are inclined with respect to the walls forming the bore 12 in the direction of plug insertion. The number of contact arms formed in each contact element may vary as a matter of design, and therefore the description with respect thereto will be limited to the single set of arms 14b, 15b and 16b. The extremity of each arm 14b, 15b and 16b is formedwith an angled dependent tip 14c, 15c and 16c, respectively, and the purpose of this specific design of the contact arms and the tips will be discussed in detail subsequently.

A cylindrical plug 17 of insulating material is formed preferably with the longitudinal axis thereof concentric with the axis of theconical bore 12. A metal pin 18 having the head'20 thereof molded in the base of the receptacle 11 may-be embodied in the plug 17 to decrease the flexibility of the plug 17, if necessary. A plurality of conductors or leads referred to generally by the numerals 21, 22 and '23 have the ends thereof soldered or other wise attached to the contact bases 14a, 16a and 15a, respectively, the three conductors extending from both ends of the connector 10 being usually bundled andwrapped together so as to form cables."

With reference to FIGURES l and 4 of the drawings, the'frusto-conical plug 13 is composed of asuitable electrical insulating material which may be the same composition as the receptacle 11, and a plurality of contact, rings referred to by the numerals 32, 33 and 34 are embedded in the tapered periphery of the plug 13 and are positioned so as to vmate with and make electrical contact with the contact elements 14, 15 and 16, respectively, of the receptacle 11 when the plug 13 is seated in the receptacle 11. Conductors or leads 21a, 22a and 23a which are to be electrically connected to the conductors 21, 22 and 23, respectively, extend from the cylindrical base end 31 of the plug 13 and terminate in leads that are soldered or otherwise connected to the contacts 32,34 and 33, respectively; The base 31 is preferably molded to'the plug 13 and includes a threaded portion 36,which may be screwed into a fixture or into 14b, 15b and 1617, respectively. The angle formed by the tips 140, 15c and 160 and the adjoining short sections of the contact arms 14b, 15b and 16b, respectively, is essentially the same angle formed by the opposite inclined sides of the V-shaped grooves 32a, 33a and 34a, respectively, so that the tips 140, 15c and 16p and the adjoining relatively short sections of the contact arms 14b, 15b and16b, respectively, contact opposite sides of V-shaped grooves, FIGURES 7 and 9, When the plug 13 is seated in the receptacle 11. The outermost radii of the contact rings 32 and 33 are preferably made less than the innermost radius of the contact; element-16, and the outermost radii of the ring 32 is also preferably made less than the innermost radius of the contact ring 33 in order to eliminate any additional resistance to the insertion of the plug into the receptacle beyond thatrequired to actually 'eflfect the interlock between mating contact elements.

As will be evident during insertion of the plug 13 into the bore 12 of the receptacle 11, the arms 14b, 15b and 1621 are forced inwardly towards the wall of the bore 12 until the tips 14c, 15c and 160 of each contact arm of the ring 14, 15 and 16 snap into the grooves 32a, 33a and 34a, respectively. Since the arms 14b, 15b and 16b are inclined in the direction of plug insertion, and the inverted W-shape of the contacts 32, 33 and 34 provide leading inclined surfaces 32b, 33b and 3412, respectively, which initially engage 'only the inclined arms 14b, 15b and 16b, comparatively little force need be applied against the base 31 of the plug 13 in order to seat the plug 13 in the receptacle 11. A bore 37 is formed COB.

centrically in the-plug 13 and the plug 17 can be inserted into the bore 37 to guide and concentrically position the plug 13 in the bore 12.

With the plug 13 seated in the receptacle 11, the tips -14c,'15c and 160 engage the sides of the V-shaped raceways or grooves'32a, 33a and 34a adjoining the surfaces 32b, 33b and 3412, respectively, and the relatively short adjoining sections of the arms 14b, 15b and'16b contact the opposite sides of the V-shaped grooves to efiectuate an interlock between the mating contact elements. The contact arms14b, 15b nad 16b are flexed inwardly towards the wall forming the bore 12 and since the plug 13 can only be withdrawn axially from the receptacle 11 therelatively short and inflexible arm's 14b, 15b and 16b abutting the sides of the grooves 32a, 33a and 34a adjoining the surfaces 32b, 33b and 34b, respectively through the tips 1403- and 16c, respectively, otter a greater resistance to the removal of the plug from thereceptacle than that offered by the contact arms during seating of the plug in the receptacle. Consequently the force required to disconnect the connector 10 is considerably greater than theforce initially required to effect the connection. Although an axial mechanical interlock exists between the contact elements, the receptaclell and the plug 13can be swiveled relative to each other without breaking the electrical contacts.

While mating contact elements and conductors for a three-wire system are shown in the accompanying drawings, the number of mating contacts and the number of conductors embodied in the connector 10 will ordinarily be merely a matter of connector design, and a plurality of conductors maybe connected to any single contact ring if so desired.

FIGURE 6 illustrates a modification of the connector 10, wherein like elements are referred to by like numerals six leads 41,'42,'43,'44, 45 and 46, extending from one end thereof, and having six leads 47, 48, 49, 50, 51 and 52, extending from the other end thereof. In this embodiment, a selective connection can be made between any lead or leads extendingfrom one eridof the connector '10 to any lead or leads extending from the other end of thev connector connected toan interlocking contact ring section on the I plug.

To illustrate specifically, the contact rings 16' and 34', FIGURES 7 and 8, are each divided into four equal and distinct contact ring sections separated one from the other by the insulation of the receptacle 11 and the plug 13', respectively, and designated by the numerals 53, 54,

55 and '56, and by the numerals 57, 58, 59 and 60, respectively. One or more leads extending from one end of the connector 10 as, for example the lead 41, may be connected to one section, as for example the section 53; and

one of the leads extending from the other end of the connector 10',- as for example the lead 47, may be connected to the mating section 57 so that an electrical connection between the conductors 47 and 51 will be created when the sect-ions 53 and 57 are rotated into electrical contact with each other. Although the sections formed by the I contact elements 16 and 34' axially interlock for reasons discussed in regard to the embodiment illustrated in FIG- URES l to 5, inclusive, the interlocking connection permits swiveling movement between the receptacle 11 and the plug 13 and thus the establishment of an electrical connection between any contact section on the plug 13 and any contact section inthe receptacle 11'. Single or plural leads may be connected to the section 53 and single or plural leads connected to other sections of the ring 16',

or single or plural leads may be connected to the receptacle rings 14 and/or 15, as needed. In the embodiment illustrated'in the drawings, lead pairs 41 and 44 are connected to the contact ring 16'; lead pairs 42 and 45 to .the contact ring lead pairs 43 and 46 to the contact ring 14',"lead' pairs '47" and 51 to the contact ring 34',

lead pairs48"and"52 'to the contact ring 33', and lead pairs49 and*50 tothe' contact ring 32'. It will be apparent to those working the art, however, that the number --of sections intowhich the receptacle. is' divided is ordinarily a matter of choice, dependent upon the number of leads which are'to' beselectively connected together by the connection.

The various sections can be rotated through any desired angle for achieving a variety of results. For example, an external ring gear 61 could be afiixed to the periphery of the base 36 of the plug 13 and a pinion 62 connected to drive the base 36 through the gear 61 from a motor M. If the receptacle 11' were held stationary in a supporting structure, timed switching could be effected between the leads extending from each end of the connector 10' by the rotation of the plug and the receptacle relative to one another at predetermined cyclic rates in opposite or the same direction determined by the motor M to effect at least one cycle of timed switching. Alternatively, the plug 13' might be held stationary while the receptacle 11' is rotated at some constant predetermined velocity to efiect at least one continuous cycle of timed switching. Obviously, the plug 13 may be manually swiveled relative to the receptacle 11' as desired in the event the plug is inadvertently turned while in the receptacle 11', or in the event the plug 13' is improperly oriented in the receptacle 11' after the demounting and subsequent reinsertion of the plug into the receptacle.

e! 6 Since the contact rings 14, 15 and 16 interlock with the contact rings 32, 33 and 34 respectively, a mechanism may be incorporated in the receptacle 11, as illustrated in FIGURES 9 and 10, to facilitate the disconnection of the plug 13 from the receptacle 11, and the tapered end of the plug 13 modified to accept this mechanism. The mechanism preferably comprises apair of levers 63 and 63', pivotally mounted by pins 64 and 64, respectively, in diametrically opposed tapered slots 65 and 65 formed in the base of the receptacle 11. The ends 66 and 66' of the levers 63 and 63' that extend into the bore 12 are preferably yoke shaped, as shown in FIGURE 10, and are positioned to bear against a shoulder 68 formed at the tapered end of the plug'13. .The yoke-shape of the ends 66 and 66' provides essentially equal distribution of pressures on each half of the shoulder 68 upon outward pivotal movement of the ends 66 and 66'. The ends 70 and 70' of the levers 63 and 63' extend from the surface of the receptacle 11 and are inclined at an angle with respect thereto so that'by gripping the ends 70 and 70', for instance between the thumb and forefinger, and squeezing, the ends 66 and 66' will force the plug 13 outwardly from the bore 12 a distance sufiicient to release the plug from interlocking contact with the receptaccle 11. It will be apparent that the lever release mechanisrn'may also be embodied in the connectcor 10' to effect breakage of the interlock between the various contact sections.

Referring now to FIGURES 11-15, inclusive, there is shown anotherembodiment of a connector 10" (FIG- URE 15) in accordance with 'the instant invention. The

connector 10" illustrated in these figures comprises a receptaclell" which is essentially identical to the'receptacle 11' discussed hereinabove, the receptacle 11" including three pairs of diametrically opposed ring contact sections similar in construction to the contact sections 14', 15' and 16illustrated in FIGURE 7. One pair of diametrically opposed contact sections is shown in FIG- URE 12, each section beingdesignated by the numeral 72 and 73, respectively. A plurality of leads 41-46',

inclusive, extend from the receptacle 11", each lead being connected to a contact ring section. The lead 41' may for example, be connected to the ring 72 whereas the lead 46' may be connectced to the contact ring 73.

-An annular groove 74 is formed in the receptacle 11" at the entrance of the receptacle, and as illustrated in FIG- 75, 76 and 77 in FIGURE 13, and one pair of diametrically opposed contact elements being illustrated in FIG- URE 14,.and referred to by the numerals 75 and 78. The two segmented contact elements forming pairs with the elements 76 and 77 are positioned in the same relative position as the contact element 78 on the tapered surface of the plug 13". The angles formed at the axis of symmetry of the receptacle 11' and the plug 13" between the ends of each arcuate contact element are preferably slightly less than 90 degrees, as illustrated in FIGURE 14. Leads 47'-52, inclusive, extend from the base end of the plug 13 and may be connected to any one of the segmented contact elements on the plug periphery. For example, the lead 47 may be connected to the contact element 75 and the lead 52 may be connected to the contact element 78. A protruding element 80 is formed at the junction between the base of the plug 13" and the tapered surface, as shown in FIGURE 13. The element 80 is designed to fit into the travel in the groove 74, FIG- URE 12, and will efiectively limit the angle of swiveling between the plug 13" and the receptacle 11" by abutting either end of the groove 74.

FIGURE 15 illustrates a cross-section taken on the defined in the appended claims.

"section line 14-14 when the plug 13" is inserted into the receptacle 11". As will be apparent, the projecting element 8% limits the total rotation of the contact elements to an angle preferably slighlty less than 180 degrees, so that'the mating elements always remain in contact, as shown in FIGURE 15. Thusthe projection 80 traveling in the groove 74 permits swiveling between plug 13 and the receptacle 11" through an are slightly less than 180 degrees and prevents internal disconnection between the contract elements and their associated leads 4-146, and 47-52, inclusive. r

In the embodiment disclosed hereinabove the plug and receptacle could be of cylindrical shape rather than of conical shape. If so desired, anextraneous locking mechanism such as a coaxial threaded bolt could beincorporated in the connector which would permit swiveling between the'plu g and receptacle and yetprovide an additional restraint against axial movement between these members.

. I While I have described and illustrated one specific em bodiment of my inventiomit will be clear that variations of the details of construction which are specifically illustrated and described may be resorted to without depart-.

ing from the'true spirit and scope of the invention as What is claimed is: 1. A multiple-lead connector of the swivel type having -male andfemale portions adapted for relative rotation on p a longitudinal axis, the combination comprising:

a female receptacle and a complementary shaped insertable male plug rotatably seated in said receptacle, said plug and receptacle being comprised of electrical insulating material;

first plurality of axially spaced arcuate contact elements of electrical conducting material concentricall contacts being positioned in mating relationship with a respective V-shaped circumferential raceway when said plug is seated in said receptacle, each of saidV-shaped contacts bearing against the sides of said respective V-shaped circumferential raceways so that electrical connection is established between respective ones of said first and second pluralities of contact elements, said leading surface radially urging said second contact elements outwardly during plug insertion, whereby the inclination of the other end of said second contact elements in the direction of plug insertion in cooperation with said leading surface results in the requirement of less force to connect the contact elements than required to disconnect the contact elements; and electrical leads connected to each of said contact elements.

2. The invention as'defined in claim l'wherein said plug andreceptacle are conically tapered in complementary relationship. I

3. The invention as defined in claim 2, and a guide member integral with said female receptacle, said guide member extending axially within said female receptacle, said male plug having a complementary opening therein for receiving saidguide member for aligning said male plug concentrically in said female'receptacle, and lever means positioned at the tapered end of said receptacle and extending therein, said lever means contacting the tapered end of said male plug, whereby the application of force to said lever. means will break the interlocking contact 7 between said contact elements upon actuation thereof.

4. The connector as claimed in claiml, wherein means are provided in said receptacle for concentrically positioning said plug in said receptacle.

5. The invention as defined in claim 1, and means coacting in said plug and receptacle for limiting the degree of swiveling movementtherein.

, tion between said plug and said receptacle so that concally fixed with respect to said axis to the inner surface of said female receptacle, said second plurality of contact elements being axially spaced and in complementary relationship to said first plurality, each of said second contact elements being formed with spring material, one end of said contact elements being secured to said female receptacle andv the other 'endbeing free'a'nd inclined in the direction of plug insertion forming the first leg of V-shaped contacts 1 plementary to said raceway, each of said V-shane nection and disconnection are effected for each of said first and second contact elements at predetermined time intervals. 7 .References Cited by the Examiner UNITED STATES PATENTS 1,090,238 3/14 Schwartz Q 219-533 7, 2,192,943 3/40 Sumner 339-258 2,298,172 10/42 Roseiet a1 339-182 X 2,476,735 7/49 Johnson 339- 7 2,551,533 5/51 Gernheuser 339-45 7 2,551,630 5/51 Page 339-182 X 2,787,771 4/57 Francis 339-81 JOSEPH D. SEERS, PrimdryExamir er.

ALFRED s. TRASK, Examiner. 

1. A MULTIPLE-LEAD CONNECTOR OF THE SWIVEL TYPE HAVING MALE AND FEMALE PORTIONS ADAPTED FOR RELATIVE ROTATION ON A LONGITUDINAL AXIS, THE COMBUSTION COMPRISING: A FEMALE RECEPTACLE AND A COMPLEMENTARY SHAPED INSERTABLE MALE PLUG ROTATABLY SEATED IN SAID RECEPTACLE SAID PLUG AND RECEPTACLE BEING COMPRISED OF A ELECTRICAL INSULATING MATERIAL; A FIRST PLURALITY OF AXIALLY SPACED ARCUATE CONTACT ELEMENTS OF ELECTRICAL CONDUCTING MATERIAL CONCENTRICALLY FIXED WITH RESPECT TO SAID AXIS TO THE OUTER SURFACE OF SAID MALE PLUG, SAID FIRST PLURALITY OF CONTACT ELE MENT HAVING AN INCLINED LEADING SURFACE IN THE DIRECTION OF PLUG INSERTION, AND HAVING A SUBSTANTIALLY VSHAPED CIRCUMFERENTIALLY RACEWAY FORMED IMMEDIATELY AFT OF SAID LEAD SURFACE, THE APEX OF THE V OF SAID RACEWAY BEING ORIENTED RADIALLY WITH RESPECT TO SAID AXIS; A SECOND PLURALITY OF AXIALLY SPACED ARCUATE CONTACT ELEMENTS OF ELECTRICAL CONDUCTING MATERIAL CONCENTRICALLY FIXED WITH RESPECT TO SAID AXIS TO THE INNER SURFACE OF SAID FEMALE RECEPTACLE, SAID SECOND PLURALITY OF CONTACT ELEMENTS BEING AXIALLY SPACED AND IN COM PLEMENTARY RELATIONSHIP TO SAID FIRST PLURALITY, EACH OF SAID SECOND CONTACT ELEMENTS BEING FORMED WITH SPRING MATERIAL, ONE END OF SAID CONTACT ELEMENTS BEING SECURED TO SAID FEMALE RECEPTACLE AND THE OTHER END BEING FREE AND INCLINED IN THE DIRECTION OF PLUG INSERTION FORMING THE FIRST LEG OF V-SHAPED CONTACTS AND TERMINATING IN AN ANGULARLY DEPENDENT TIP FORMING THE SECOND LEG OF SAID V-SHAPED CONTACTS COMPLEMENTARY TO SAID RACEWAY EACH OF SAID V-SHAPED CONTACTS BEING POSITIONED IN MATING RELATIONSHIP WITH A RESPECTIVE V-SHAPED CIRCUMFERENTIAL RACEWAY WHEN SAID PLUG IS SEATED IN SAID RECEPTACLE, EACH OF SAID V-SHAPED CONTACTS BEARING AGAINST THE SIDES OF SAID RESPECTIVE V-SHAPED CIRCUMFERENTIAL RACEWAYS SO THAT ELECTRICAL CONNECTION IS ESTABLISHED BETWEEN RESPECTIVE ONES OF SAID FIRST AND SECOND PLURALITIES OF CONTACT ELEMENTS, SAID LEADING SURFACE RADIALLY URGING SAID SECOND CONTACT ELEMENTS OUTWARDLY DURING PLUG INSERTION, WHEREBY THE INCLINATION OF THE OTHER END OF SAID SECOND CONTACT ELEMENTS IN THE DIRECTION OF PLUG INSERTION IN COOPERATION WITH SAID LEADING SURFACE RESULTS IN THE REQUIREMENT OF LESS FORCE TO CONNECT THE CONTACT ELEMENTS THAN REQUIRED TO DISCONNECT THE CONTACT ELEMENTS; AND ELECTRICAL LEADS CONNECTED TO EACH OF SAID CONTACT ELEMENTS. 